Method of assigning transmission channels in a telecommunications network and user station

ABSTRACT

A method of assigning transmission channels in a telecommunications network and a user station are provided, which facilitate an increase in the capacity of a telecommunications network. The telecommunications network may include multiple base stations and mobile stations, the transmission channels being provided for transmitting signals between the base stations and the mobile stations. In uncoordinated operation of the base stations, at least one of the transmission channels is assigned for transmitting signals between one of the base stations and one of the mobile stations as a function of a channel measurement, in which the transmission power on all possible transmission channels is measured, if the previously measured transmission power on this transmission channel is minimal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/705,523 filed on Nov. 10, 2003 now U.S. Pat. No. 7,551,932, which isa continuation of U.S. patent application Ser. No. 10/377,443 filed Feb.28, 2003 now abandoned and U.S. patent application Ser. No. 10/148,854filed Jun. 3, 2002 now abandoned, which is a National Phase ofApplication No. PCT/DE00/03912 filed on Nov. 9, 2000, which claimspriority to prior German Patent Application No. 199 57 740.4 filed onDec. 1, 1999 and German Patent Application No. 100 08 838.4 filed onFeb. 25, 2000, all of which are hereby incorporated by reference intheir entirety.

FIELD OF THE INVENTION

The present invention relates to a method of assigning transmissionchannels in a telecommunications network and to a user station.

BACKGROUND INFORMATION

A method and a device for operation in an indoor CDMR telecommunicationssystem are referred to in European Published Patent Application No. 0865 172, in which two or more wireless communications systems areoperated superimposed. One of the two systems is an indoor system andthe other is an outdoor system. The indoor system monitors the operationof the outdoor system and detects which part of the available radioresources are sometimes not used or are interference-free in the outdoorsystem. The indoor system dynamically selects an unused outdoor channelfor indoor operation. The indoor radio traffic is divided into TDD timeslots, which include the time slots for monitoring the existing radioconnections on other outdoor channels, so that rapid changes arepossible in accordance with changing traffic and changing interferenceconditions. A threshold value comparison is performed during theselection of the channels.

In mobile radio systems of the third generation, for example inaccordance with the GSM standard (Global System for MobileCommunications) or the UMTS standard (Universal Mobile TelecommunicationSystem) or the like, two concepts (or modes) may be provided fortransmitting signals via an air interface between a base station and amobile station, depending on the transmission resource used. If variousfrequency bands are provided as a transmission resource, an FDD mode(Frequency Division Duplex) may be used, in which two differentfrequency bands are used to transmit the signals from the mobile stationto the base station in the uplink transmission direction and from thebase station to the mobile station in the downlink transmissiondirection. If time slots are used as a transmission resource, the TDDmode (Time Division Duplex) may be used, in which different time slotsare used for the uplink transmission direction and the downlinktransmission direction, while using the same frequency band. Furtherchannel separation is possible for both modes in this case.

However, in uncoordinated operation the base stations may not be linkedvia a higher-order system, so that coordinated code assignment may notbe possible. Such operation may be advisable, for example, for the homesector with cordless telephones, in which, under certain circumstances,many individual base stations may be operated independently from oneanother. In this case, the code assignment may not be coordinated.Therefore, only one base station may be active per transmissionresource, for example, per time slot or per frequency band, but evenusing multiple different codes for this purpose. This transmissionresource may be occupied for a neighboring base station, since thestation may not know the codes used. A power measurement may permit theneighboring base station to detect whether a transmission resource isoccupied. If so, the neighboring base station may substitute othertransmission resources, for example, other time slots or frequencybands.

SUMMARY OF THE INVENTION

It is believed that an exemplary method according to the presentinvention for assigning transmission channels in a telecommunicationsnetwork and an exemplary user station according to the present inventionmay have the advantage in that, in uncoordinated operation of basestations, at least one of the transmission channels is assigned fortransmitting signals between one of the base stations and one of themobile stations as a function of a channel measurement. To perform thechannel measurement, the transmission power on all possible transmissionchannels is measured, if the previously measured transmission power onthe transmission channel is minimal. In this manner, the existingtransmission channels may be optimally distributed on connections set upor to be set up for transmitting signals between the base stations andthe mobile stations, so that the capacity of the telecommunicationsnetwork, and therefore the number of connections to be set upsimultaneously, may be increased, or at least maximized. The sametransmission channel may even be used simultaneously by various basestations if, for example, due to a limited range, the various basestations influence one another insignificantly or not at all.

It may be advantageous that codes are provided, through which at leastone transmission resource, for example, a time slot or a frequency band,is spread using multiple transmission channels for transmitting signalsbetween the base stations and the mobile station, and that the channelmeasurement includes a code measurement, in which a received signal foreach transmission resource is despread using each allowed code tomeasure the transmission power of each of the transmission channels. Inthis manner, a transmission resource, for example, a time slot or afrequency band, may be used jointly and simultaneously by different basestations and/or by multiple transmission channels. Through the divisionof the transmission resources, the capacity of the telecommunicationsnetwork, and therefore the number of connections capable of being set upsimultaneously, may be increased.

It is believed to be advantageous in that the channel measurement forthe assignment of at least one of the transmission channels between oneof the base stations and one of the mobile stations is performed while aconnection is being established. In this manner, the capacity of thetelecommunications network is used at the earliest possible time forevery connection to be set up.

It is also believed to be advantageous that the channel measurement forthe assignment of at least one of the transmission channels is performedduring an existing connection between one of the base stations and oneof the mobile stations, that the connection quality of the existingconnection is measured in parallel, and, if the connection quality fallsbelow a preselected value, that a channel change is performed and atleast one new transmission channel is assigned as a function of thechannel measurement of the existing connection. In this manner, dynamicchannel assignment may be implemented for one or more existingconnections, so that the transmission channels previously assigned to anexisting connection have the highest possible connection quality.

In addition, it is believed to be advantageous that, for at least one ofthe base stations, specific information is transmitted via a broadcastchannel to all mobile stations in the reception range of the at leastone base station, and that the broadcast channel is changed if theinterference detected thereon exceeds a preselected value. In thismanner, the broadcast channel may be dynamically assigned to at leastone of the base stations, the broadcast channel previously usedreceiving as little interference as possible.

It is believed that a further advantage is that at least one of thetransmission channels is reserved for use as a broadcast channel. Inthis manner, the expense and time required for the mobile stations tofind the broadcast channel is reduced, since the stations may find thebroadcast channel from an already selected or preselected set oftransmission channels.

It is also believed to be advantageous in that, if the transmissioncapacity of the established transmission channels is insufficient, atleast one transmission channel scrambled using a new scrambling code isassigned for transmitting signals between one of the base stations andone of the mobile stations as a function of a channel measurement, inwhich the transmission power on all possible transmission channels ismeasured after scrambling, using a scrambling code, if the transmissionpower measured on the scrambled transmission channel is minimal. In thismanner, it may be avoided that a base station in uncoordinated operationcannot find a free transmission channel because, for example, one ormore other base stations already occupy all of the transmissionchannels. Rather, the number of transmission channels and therefore thedata rate may be further increased by using scrambling codes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an exemplary user station according to thepresent invention.

FIG. 2 is a code-time slot diagram.

FIG. 3 is a diagram showing an exemplary first arrangement of base andmobile stations in a mobile radio network according to the presentinvention.

FIG. 4 is a diagram showing an exemplary second arrangement of base andmobile stations in a mobile radio network according to the presentinvention.

FIG. 5 shows a schematic block diagram (flowchart) of an exemplarymethod according to the present invention.

DETAILED DESCRIPTION

In FIG. 1, 15 identifies a user station of a telecommunications network5. Telecommunications network 5 may be implemented, for example, as alandline network or as a mobile radio network. If telecommunicationsnetwork 5 is a mobile radio network, user station 15 may include a basestation 11, 12 or a mobile station 21, 22, as shown, for example, inFIG. 3. For the description to follow, it is presumed, for exemplarypurposes only, that telecommunications network 5 is a mobile radionetwork and that user station 15 is a base station 11, 12 or a mobilestation 21, 22. Mobile radio system 5 and user station 15 may beimplemented, for example, according to the GSM standard (Global Systemfor Mobile Communication), the UMTS standard (Universal MobileTelecommunication System) or the like.

User station 15 illustrated in FIG. 1 includes a receiver 25, to which areceiving aerial 60 is connected. As shown in FIG. 1, user station 15also includes a transmitter 35, to which a transmitting aerial 70 isconnected. Receiving aerial 60 and transmitting aerial 70 may also becombined into a combined transmitting/receiving aerial by using amultiplexer, for example. Receiver 25 is connected on the output side toan input of code measurement arrangement 30 for code measurement and isalso connected to an input of a despreading device 45. Codes of a firstcode memory 51 are also supplied to code measurement arrangement 30 forcode measurement. In addition, at least one code of a second code memory52 is supplied to despreading device 45. Code measurement arrangement 30for code measurement is connected on the output side to an input ofchannel measurement arrangement 10 for channel measurement. Despreadingdevice 45 is connected on the output side to an input of a connectionquality arrangement 40 for measuring the connection quality. An outputof connection quality arrangement 40 is also supplied to channelmeasurement arrangement 10. Channel measurement arrangement 10 isconnected on the output side to an input of a channel assignmentarrangement 20 for channel assignment, the output of which is suppliedto transmitter 35.

In the following description, for exemplary purposes only, both firstbase station 11 and second base station 12 in mobile radio network 5 asshown in FIG. 3 are constructed similarly to the user station 15 shownin FIG. 1, and both first mobile station 21 and second mobile station 22are constructed similarly to user station 15 shown in FIG. 1. As shownin FIG. 3, first base station 11 covers a first radio cell 61, in whichthe first base station 11 may communicate with mobile stations usingradio signals. Second base station 12 covers a second radio cell 62, inwhich the second base station 11 may communicate with mobile stationsusing its radio signals. First mobile station 21 is positioned in firstradio cell 61, while second mobile station 22 is positioned in secondradio cell 62. A first connection 41 is to be established between firstbase station 11 and first mobile station 21, while a second connection42 is to be established between second base station 12 and second mobilestation 22.

Two different concepts (or modes) may be provided for first connection41 and for second connection 42: FDD mode (Frequency Division Duplex),in which two different frequency bands are used as a transmissionresource for the uplink transmission direction from respective mobilestations 21, 22 to assigned base stations 11, 12; and TDD mode (TimeDivision Duplex), in which different time slots in the same frequencyband are used as a transmission resource for the uplink transmissiondirection and the downlink transmission direction. In both modes, therespective transmission resources may be spread into multipletransmission channels by using codes C based, for example, on a CDMAmethod (Code Division Multiple Access) for further channel separation.In this case, one frequency band or one time slot may each be spreadinto multiple transmission channels by using different codes. One suchtransmission resource, for example, one time slot or one frequency band,may be used simultaneously by various connections and/or by the sameconnection in the uplink or in the downlink transmission direction byusing different codes, so that the capacity of mobile radio network 5and/or the number of connections which may be set up in mobile radionetwork 5 may be increased by increasing the number of usabletransmission channels. If, for example, the transmission resources areimplemented as time slot ZS, spreading into multiple transmissionchannels by using different codes C is illustrated in FIG. 2. In thiscase, fifteen time slots are provided per transmission frame on theabscissa numbered from 0 to 14 in FIG. 2. Four different codes C from 1to 4 are plotted on the ordinate, so that each time slot ZS is spreadinto four different transmission channels, which differ from one anotherdue to different coding, using the same spread factor 4. Thetransmission channels created in this manner are illustrated as rasterelements in the code-time slot diagram shown in FIG. 2 and areindicated, as a whole, using reference number 1.

For example, time slots for transmitting signals in mobile radio network5 may be used as a transmission resource. In this case, base stations11, 12 are operated uncoordinatedly and are not connected via a higherorder system, so that coordinated code assignment may not be possible.Such uncoordinated operation may be used for the home sector when usingmobile stations 21, 22 implemented as cordless telephones, since manyindividual base stations may be, under certain circumstances, operatedindependently from one another and therefore uncoordinatedly. For acordless telephony application, telecommunications network 5, basestations 11, 12, and mobile stations 21, 22 may be implemented, forexample, in accordance with the DECT standard (Digital European CordlessTelecommunications). In such uncoordinated operation, coordinated codeassignment for the individual connections to be set up between basestations 11, 12 and mobile stations 21, 22 may no longer be possible.

Below, first connection 41 to be set up between first base station 11and first mobile station 21 is described for exemplary purposes only.While the connection is being established, code measurement arrangement30 checks, either in first base station 11 or in first mobile station21, which codes C in which time slots ZS are already occupied by otherconnections. For this purpose, the signal for each of fifteen time slotsZS received in first base station 11 and/or first mobile station 21should be despread using each permitted code C stored in first codememory 51, corresponding to CDMA demodulation. Through despreading incode measurement arrangement 30, all transmission channels 1, each ofwhich are implemented as a code/time slot combination, are extractedfrom the received signal. As shown in FIG. 2, sixty transmissionchannels result from the multiplication of fifteen time slots ZS by fourcodes C. Extracted transmission channels 1 are then supplied to channelmeasurement arrangement 10, which measures the transmission power on allextracted transmission channels 1. First connection 41 to be set up isthen assigned to at least one of transmission channels 1 by channelassignment arrangement 20. In this case, the transmission channel with aminimal previously measured transmission power is assigned to firstconnection 41. For a full duplex connection to be set up between firstbase station 11 and first mobile station 21, the exemplary methodaccording to the present invention is to be performed both for theuplink transmission direction from first mobile station 21 to first basestation 11 and for the downlink transmission direction from first basestation 11 to first mobile station 21, so that at least one transmissionchannel may be used for first connection 41 in each of the twotransmission directions. FIG. 3 illustrates the downlink transmissiondirection with arrows for both first connection 41 and for secondconnection 42. In this case, the channel measurement for assigning atleast one of transmission channels 1 may be performed in the uplinktransmission direction by first base station 11 and the channelmeasurement for assigning at least one of transmission channels 1 may beperformed in the downlink transmission direction by first mobile station21. The assignment of the at least one of transmission channels 1selected through the channel measurement in the uplink transmissiondirection may then be performed by first base station 11. The assignmentis performed by its channel assignment arrangement 20, which, viatransmitter 35 of first base station 11, transmits a correspondingsignal to first mobile station 21 in regard to the at least one assignedtransmission channel. In a corresponding manner, the assignment of atleast one of transmission channels 1 in the downlink transmissiondirection may be performed by first mobile station 21, the channelassignment arrangement 20 of which transmits a signal to first basestation 11 via corresponding transmitter 35 so that first base station11 may know the at least one transmission channel selected for thedownlink transmission direction.

According to this exemplary embodiment of the present invention, a firsttransmission channel 31, which represents a combination of the thirdtime slot and the second code shown in the code/time slot diagram ofFIG. 2, is assigned for the downlink transmission direction of firstconnection 41.

Before establishing first connection 41, first base station 11 initiallyselects one of transmission channels 1 and uses it as a broadcastchannel. According to this exemplary embodiment of the presentinvention, base station 1 first selects a combination of first time slotand third code, as shown in the code/time slot diagram of FIG. 2, asbroadcast channel 50. The specific information for first base station 11is transmitted via broadcast channel 50 to all mobile stations locatedin first radio cell 61. This specific information may contain, forexample, the codes used by first base station 11, an identification offirst base station 11, synchronization information, information abouttransmission channels and/or code/time slot combinations already used,information about paging messages that exist for one or more of themobile stations located in first radio cell 61, etc. First mobilestation 21 located in first radio cell 61 may therefore recognize firstbase station 11 assigned to it by synchronization on broadcast channel50 and analysis of the information transmitted via this broadcastchannel 50.

Each of transmission channels 1 may be used as broadcast channel 50. Toavoid interference of the broadcast channels of different base stations11, 12, the broadcast channel may be changed if needed, for example, ifinterference from other broadcast channels or transmission channelsdetected on the broadcast channel exceeds a preselected value. To reducethe outlay of first mobile station 21 and to find broadcast channel 50,either a special code C may be reserved and/or preselected for anydesired time slot ZS or a specific time slot ZS may be reserved and/orpreselected for any desired code C for the broadcast channel of firstbase station 11, or a prereserved selection of any desired specifiedtransmission channels and/or code/time slot combinations may be used asa broadcast channel 50.

During existing first connection 41, the transmission power iscyclically remeasured on all possible transmission channels 1, so that apicture of free and occupied and/or of malfunctioning and functioningtransmission channels is continuously available. In parallel, theconnection quality of existing first connection 41 is measured byconnection quality arrangement 40 in first base station 11 and/or infirst mobile station 21, for example, on the basis of the transmissionerror rate. If the connection quality falls below a preselected value, achannel change to another transmission channel and/or another code/timeslot combination may be performed. For this purpose, the transmissionpowers of the transmission channels and/or code/time slot combinationspreviously not used for first connection 41 should be continuouslymonitored. For the channel change, first base station 11 measures theconnection quality of first connection 41 in the uplink transmissiondirection and first mobile station 21 measures the correspondingconnection quality of first connection 41 in the downlink transmissiondirection. If the connection quality falls below a preselectedthreshold, the channel changes in the uplink and downlink transmissiondirections occur independently from one another. For this purpose, theestablishment of the connection may be accomplished in three manners. Inthe first manner, the channel change is performed solely by base station11, since it already knows all of the transmission channels it uses. Forthis purpose, first mobile station 21 transmits, via its transmitter 35,the measurement results of the connection quality or the request for achannel change due to such measurement results for the downlinktransmission direction to first base station 11. In the second manner,mobile station 21 first initiates the channel change in the downlinktransmission direction and first base station 11 initiates the channelchange in the uplink transmission direction. The third manner isoriented to the DECT standard, in which the channel change is initiatedby first mobile station 21 both in the uplink and in the downlinktransmission directions, and first base station 11 merely signals tofirst mobile station 21 that a channel change is necessary in the uplinktransmission direction. Regardless of whether the connection quality ismeasured in first base station 11 or in first mobile station 21, thismeasurement is performed in that the transmission channels to beevaluated for first connection 41 are extracted from the signal receivedvia corresponding receiver 25 by respective despreading device 45 withthe aid of the code(s) assigned to first connection 41, which is/arestored in second code memory 52, and supplied to connection qualityarrangement 40. In connection quality arrangement 40, the connectionquality of the transmission channels for first connection 41 may thenbe, for example, measured on the basis of the transmission error rate.In parallel, code measurement arrangement 30 extracts all transmissionchannels 1 from the signal received via receiver 25 with the aid of thecodes stored in first code memory 51 and supplies these transmissionchannels to the channel measurement in first channel measurementarrangement 10, which measures the transmission power on extractedtransmission channels 1. Channel measurement arrangement 10 checks, withreference to the value of the connection quality of the respectivetransmission channel of first connection 41 determined by connectionquality arrangement 40, whether this value falls below a preselectedvalue for the connection quality. If so, channel measurement arrangement10 selects the transmission channel that has the minimum transmissionpower and causes channel assignment arrangement 20 to subsequently usethis transmission channel for first connection 41 instead of thecorresponding transmission channel measured by connection qualityarrangement 40, which has too low a connection quality.

FIG. 3 illustrates first base station 11 and second base station 12operated independently from one another. One mobile station 21, 22 isregistered in each of two base stations 11, 12. First mobile station 21is initially located at a first position A within first radio cell 61,illustrated in FIG. 3, and has a first transmission/reception range 71.Second mobile station 22 is located at a third position C in secondradio cell 62 and includes a second transmission/reception range 72.First mobile station 21 may transmit and receive radio signals withinfirst transmission/reception range 71. Signals transmitted outside thefirst transmission/reception range 71 may no longer be received by firstmobile station 21. In addition, signals transmitted by first mobilestation 21 outside first transmission/reception range 71 may no longerbe received in second base station 12 and in second mobile station 22.The same is true for second transmission/reception range 72 of secondmobile station 22. In this case, the same transmission channels and/orcode/time slot combinations are simultaneously used in the uplink and inthe downlink transmission directions for both first connection 41 andsecond connection 42. As shown in FIGS. 2 and 3, first transmissionchannel 31 is used for the downlink transmission direction for bothfirst connection 41 and second connection 42. If a channel changeoccurs, it applies for both the uplink and the downlink transmissiondirections, both being independent from one another. Both mobilestations 21, 22 are sufficiently distant from one another so that theirtransmission/reception ranges 71, 72 do not overlap and do not mutuallyinterfere in their transmission channels. The instantaneous transmissionquality is measured for both connections 41, 42 in the manner describedabove, both in the uplink and in the downlink transmission directions,for example, by analyzing the transmission or bit error rates. Bothmobile stations 21, 22 cyclically establish the transmission power ofall possible transmission channels 1 and/or code/time slot combinations,by despreading all transmission channels 1 and/or code/time slotcombinations in the way described above via code measurement arrangement30 and establishing the transmission power on transmission channels 1extracted in this way via channel measurement arrangement 10 and storingthis transmission power in tabular form in a memory (not shown in FIG.1). Smaller values of the transmission power measured signal little orno interference in this case. If first mobile station 21 now moves fromfirst position A into second position B and therefore, as shown in FIG.3, into second radio cell 62 and/or into second transmission/receptionrange 72 of second mobile station 22, the mutual interference of thetransmission channels used increases and the connection quality istherefore reduced. If it falls below the preselected value for theconnection quality, then a channel change is initiated in the waydescribed above for at least one of the two connections 41, 42 and thisconnection is assigned at least one new transmission channel in theuplink and/or in the downlink transmission direction.

In a modification of the exemplary embodiment described with referenceto FIG. 2, despreading individual time slots ZS by more or less thanfour codes C may also be provided.

According to this exemplary embodiment of the present invention,however, all fifteen time slots ZS per transmission frame are spreadusing four codes C, so that a total of 60 transmission channels results.Both first base station 11 and second base station 12 may thus access 60such transmission channels if there is no interference, so that a totalof 60 connections may theoretically be established simultaneously withinthe geographical range defined by first radio cell 61 and by secondradio cell 62, if the reservation of transmission channels for settingup a broadcast channel for each of the two base stations 11, 12 is notconsidered.

Another exemplary embodiment according to the present invention isdescribed with reference to FIG. 4. In this case, 310 identifies a radiocoverage area, for example, a shared radio cell, in which a third basestation 110 and a fourth base station 210 are operated independently anduncoordinatedly from one another. In this exemplary embodiment, TDDoperation using a CDMA method is described for exemplary purposes.Telecommunications network 5 may be implemented as a mobile radionetwork or as a cordless telephone network.

Third base station 110 and fourth base station 210 are locallypositioned directly adjacent to one another and only separated from oneanother by a wall 320, which does not, however, represent an obstructionfor the radio frequencies used for transmission, but rather indicatesthat both base stations 110, 210 are, for example, positioned inneighboring office rooms. Third base station 110 supplies a third mobilestation 120 via a third connection 140 and a fourth mobile station 130via a fourth connection 150. Third connection 140 and fourth connection150 may represent radio connections in the TDD mode. In an exemplaryscenario, third connection 140 and fourth connection 150 together mayrequire a data rate so high that all of the transmission channels of theTDD mode available are used. Fourth base station 210 then wishes toestablish a fifth connection 240 to a fifth mobile station 220 in theTDD mode using the CDMA method. For this purpose, as in the exemplaryembodiment described with reference to FIG. 3, all transmission channelsavailable in radio coverage area 310, i.e., code/time slot combinations,are checked as to whether they are already occupied or haveinterference, which causes them to fall below the preselected value forconnection quality. If so, the corresponding transmission channel isunusable. If not, it is usable. Fourth base station 210 recognizeswhether all transmission channels in radio coverage area 310 areunusable and/or whether the number of the usable transmission channelsstill available for fifth connection 240 is smaller than the number oftransmission channels necessary for fifth connection 240.

To permit fifth connection 240 to be established without producingunacceptable interference for already existing third connection 140 andalready existing fourth connection 150, fourth base station 210 changesa scrambling code used jointly with third base station 110.

One single scrambling code is used within a radio cell. All signalstransmitted in the radio cell are scrambled using this scrambling code.To prevent signals of different neighboring radio cells from mutuallyinterfering with one another, for example, if CDMA is used, the signalsare scrambled using different scrambling codes, i.e., neighboring radiocells use different scrambling codes. The various scrambling codes areselected so that they have the smallest possible cross correlation withone another for any desired mutual time shifts. The spreading of thesignals within a radio cell is then performed using orthogonal codes,which are mutually uncorrelated due to the synchronous transmission.

In another scenario, this concept is abandoned in the case ofinsufficient transmission capacity, in that in radio coverage area 310,which is to represent a shared radio cell, a scrambling code isintroduced for fourth base station 210 which is different from thescrambling code of third base station 110.

Subsequently, the search for and possible assignment of sufficientinterference-free transmission channels for fifth connection 240 to beestablished are repeated in the way described above with reference toFIGS. 1 to 3, but using the new scrambling code.

This procedure is repeated until a sufficient number of sufficientlyinterference-free transmission channels have been found and assigned tofifth connection 240.

If enough sufficiently interference-free transmission channels are notfound, a further scrambling code may be checked in the way describedabove and used if necessary. This procedure may be repeated until an“unused” scrambling code having enough sufficiently interference-freetransmission channels is found.

On the basis of the scenario described above, a sixth connection 250 maybe established in the TDD mode using the CDMA method from fourth basestation 210 to a sixth mobile station 230, as described with referenceto FIG. 4. In another exemplary scenario, fifth connection 240 requiresa data rate so high that insufficient transmission channels areavailable for sixth connection 250, even with scrambling using the newscrambling code because, for example, all transmission channels havingthe new scrambling code are used by fifth connection 240. The newscrambling code is referred to below as the first new scrambling code.

For sixth connection 250, fourth base station 210 may now introduce asecond new scrambling code, which differs from the first new scramblingcode and the original scrambling code used, for example, by fourth basestation 210, all scrambling codes used having the characteristic of lowmutual cross correlation for any desired mutual time shift.

The search for and possible assignment of sufficient interference-freetransmission channels for sixth connection 240 to be established arethen performed again in the way described above with respect to FIGS. 1to 3, but using the second new scrambling code.

This procedure is also repeated until a sufficient number ofsufficiently interference-free transmission channels is found andassigned to sixth connection 240.

If enough sufficiently interference-free transmission channels are notfound, a further scrambling code may be checked and used in the waydescribed above. This procedure may be repeated until an “unused”scrambling code having enough sufficiently interference-freetransmission channels is found.

For a connection to be established between one of base stations 110, 210and one of mobile stations 120, 130, 220, 230, various scrambling codesmay be used if the data rate necessary for this connection and theavailable sufficiently interference-free transmission channels requireit.

Therefore, if the connection quality of all or many transmissionchannels is, for example, worsening due to interference from theuncoordinated operation described above, the influence of interferencemay be reduced by substituting other scrambling codes.

In this case, the use of different scrambling codes may lead to thetransmission capacity of locally delimited telecommunications network 5in uncoordinated operation being many times greater than that incoordinated operation.

The search for previously unused scrambling codes may either beperformed according to a fixed sequence or by random selection of ascrambling code.

Third base station 110, fourth base station 210, third mobile station120, fourth mobile station 130, fifth mobile station 220, and sixthmobile station 230 are each to have the construction and the mode ofoperation described for user station 15 shown in FIG. 1. Simultaneously,channel measurement arrangement 10 may produce the new scramblingcode(s) and perform appropriate scrambling of the transmission channelsto be measured.

The measurement and assignment of transmission channels scrambled, andtherefore also the change of the scrambling code, may be performed bothin base stations 11, 12, 110, 210, for example, for the uplinktransmission direction, and in mobile stations 21, 22, 120, 130, 220,230, for example, for the downlink transmission direction.

The search for new scrambling codes may be performed permanently or asneeded.

1. A mobile telecommunications system, comprising: at least one basestation; a plurality of user stations, wherein the at least one basestation and the plurality of mobile stations form a telecommunicationsnetwork; an assigning arrangement to assign transmission channels in thetelecommunications network, wherein the transmission channels areprovided for transmitting signals between the at least one base stationand the plurality of mobile stations, by performing, in an uncoordinatedoperation of the at least one base station for establishing a connectionbetween the at least one base station and one of the mobile stations,assigning an uplink and a downlink transmission channel for thetransmission of signals between the at least one base station and theone of the mobile stations; and a channel measuring arrangement to inwhich the at least one base station and the one of the mobile stationseach perform a channel measurement on all possible transmission channelsto determine whether such transmission channels are below a pre-selectedvalue for connection quality, and said uplink and downlink transmissionchannels are assigned based on said measurement, and thereafter the atleast one base station and the one of the mobile stations repeatedlyre-measure all of the possible transmission channels not previously usedto determine whether such transmission channels are below a pre-selectedvalue for connection quality; wherein the channel measurement on allpossible transmission channels is performed before the assigning of theuplink channel and the downlink channel, and wherein the one of themobile stations performs the channel measurement for channeltransmissions in the downlink direction and the at least one basestation performs the channel measurement for channel transmissions inthe uplink direction with independent assignment of the uplink channeland the downlink channel.
 2. The system of claim 1, wherein codes areused to spread at least one transmission resource into a plurality ofthe transmission channels, wherein the channel measurement includes acode measurement, in which a received signal for each transmissionresource is despread using allowed ones of the codes to measure thetransmission power in each of the transmission channels.
 3. The systemof claim 2, wherein the codes are provided for spreading at least one ofa time slot and a frequency band.
 4. The system of claim 1, wherein aconnection quality of the existing connection is measured in parallel,and, if the connection quality falls below a preselected value, achannel change is performed and at least one new transmission channel isassigned as a function of a channel measurement of the existingconnection.
 5. The system of claim 1, wherein at least one of the basestations transmits specific information via a broadcast channel to allof the mobile stations within a reception range of the at least one ofthe base stations, and the broadcast channel is changed if aninterference detected on the broadcast channel exceeds a preselectedvalue.
 6. The system of claim 5, wherein at least one of thetransmission channels is reserved for use as the broadcast channel'. 7.The system of claim 1, wherein if a transmission capacity of thetransmission channels established for assignment is not sufficient, thefollowing are performed: (A) scrambling at least one of the transmissionchannels with a new scrambling code; and (B) assigning the at least onescrambled transmission channel for transmitting signals between one ofthe base stations and one of the mobile stations as a function of achannel measurement, wherein a transmission power on all possible onesof the transmission channels is measured after scrambling the at leastone transmission channel, if a transmission power measured on the atleast one transmission channel is minimal.
 8. The system of claim 1,wherein codes are used to spread at least one transmission resource intoa plurality of the transmission channels, wherein the channelmeasurement includes a code measurement, in which a received signal foreach transmission resource is despread using allowed ones of the codesto measure the transmission power in each of the transmission channels,wherein the codes are provided for spreading at least one of a time slotand a frequency band, wherein a connection quality of the existingconnection is measured in parallel, and, if the connection quality fallsbelow a preselected value, a channel change is performed and at leastone new transmission channel is assigned as a function of a channelmeasurement of the existing connection.
 9. The system of claim 8,wherein at least one of the base stations transmits specific informationvia a broadcast channel to all of the mobile stations within a receptionrange of the at least one of the base stations, and the broadcastchannel is changed if an interference detected on the broadcast channelexceeds a preselected value.
 10. The system of claim 9, wherein at leastone of the transmission channels is reserved for use as the broadcastchannel.
 11. The system of claim 8, wherein if a transmission capacityof the transmission channels established for assignment is notsufficient, the following are performed: (A) scrambling at least one ofthe transmission channels with a new scrambling code; and (B) assigningthe at least one scrambled transmission channel for transmitting signalsbetween one of the base stations and one of the mobile stations as afunction of a channel measurement, wherein a transmission power on allpossible ones of the transmission channels is measured after scramblingthe at least one transmission channel, if a transmission power measuredon the at least one transmission channel is minimal.